The macro-scale. Seismic monitoring of CO₂ sequestration

Abstract

Storage of carbon dioxide (CO₂) in deep saline aquifers and aging oil reservoirs is a valid alternative approach for reducing the amount of greenhouse gases in the atmosphere. This procedure can be modeled by the combined use of multi-phase fluid flow and wave propagation. The flow simulator is used to model the CO₂ injection, and seismic monitoring is applied to determine the spatiotemporal distribution of CO₂ after several years of injection. The simultaneous flow of brine and CO₂ is modeled with the Black-Oil formulation for two-phase flow in porous media, while wave propagation is formulated using an isotropic viscoelastic model. The CO₂ saturation and pressure data computed with the flow simulator is used in a petrophysical model to determine the complex bulk and shear moduli of the formation. Wave propagation is performed using a finite element domain decomposition procedure. The simulation is used to model CO₂ injection and flow and compute time-lapse seismograms corresponding to the Utsira aquifer at Sleipner field with the objective of identifying the spatio-temporal distribution of CO₂ after injection.